In game machines which realize computer games such as so-called action type games and role playing games, a leading character (player character) in a game image displayed on a screen of a display device is controlled according to an operation signal from an input device (controller pad) operated by a player, so that the story of the game proceeds. Particularly in recent years, according to improvement of hardware performance, a game image such that a player character acts in the virtual three-dimensional space is provided in a form of three-dimensional graphics, thereby heightening the presentation effect of the game.
In three-dimensional graphics, a spatial position relationship of an object in a visual line direction is obtained from a visual point position in the virtual three-dimensional space based on three-dimensional data expressing the object, an image process such as a rendering process is executed, so that the object is expressed three-dimensionally. That is to say, in games utilizing three-dimensional graphics, a player character and another object captured from the visual point position are expressed three-dimensionally, and the visual point position and the visual line are moved according to operations by the player or game scenes. Game images in which the virtual three-dimensional space is expressed in such a manner are provided.
Game machines, which provide game images where the virtual three-dimensional space is expressed from a specified camera angle in games such as action type games using a lot of three-dimensional graphics, provide the following game images, for example. In the game images, a character which moves in response to an operation by the planer is tracked to be photographed by a virtual camera arranged in an upper-backward position of the character. In the case where the thing which is present besides far background such as mist is expressed, an effect image which draws the landscape is synthesized with the far background and the character image to be displayed, so that various things which come into the visual field of the virtual camera are expressed, thereby providing the sense of reality.
In the case where an object which moves in the virtual three-dimensional space is to be displayed, like an image which is tracked to be photographed by the virtual camera is displayed on a display unit of the display device. Since a size of a display area is, however, limited, only a range of the viewing angle where the virtual camera is the visual point is displayed. For this reason, a screen, on which the arrangement relationship of a specified object such as its current position and a relative position relationship between the specified object and another mobile object in a course map where a moving range is limited is shown as a pattern in a reduced-size graphic (hereinafter, radar image), as well as a main screen is displayed in order to understand a condition of a range which is not displayed in a range captured by the virtual camera (for example, see Patent Document 1).
Further, the game machines which display radar images include the following game machines (for example, see Non-Patent Document 1). In this game machine, like a game where a player's battleplane is operated to attack an opponent's battleplane, a circular radar frame obtained by patterning a radar, for example, as well as a visual field image captured from the self battleplane is displayed on a display unit, a “visual field display” representing a portion actually displayed on a main screen is displayed as a radar image in a radar detection space, and a player's sight is set on the opponent's battleplane in the radar image so as to attack the opponent's battleplane. At this time, on the radar image which represents the radar detection space, a character to be operated by the player is arranged on the center or lower-end center, and a position of the object is displayed as a small window represented by a light spot or a symbol with the character looking down the ground vertically. A fan shaped (or (inverted) triangular) section whose center (apex) shows the character to by operated by the player is displayed within the small window, so that a visual field portion is expressed.
In recent years, the display devices include two types of display devices whose screen ratio (aspect ratio) is 4:3, namely, have a normal screen (standard screen) and 16:9, namely, have a wide screen. In image processing devices such as game machines which display virtual objects, however, even if the aspect ratio is different from the above aspect ratios, a player feels less discomfort at the screen unlike television broadcasting which provides an actual live image. For this reason, images are generally processed without taking the screen ratio into consideration. When, however, images on the standard screen created by the image processing devices such as the game machines are directly displayed on the wide screen, defects such as non-image portions on right and left portions occur.
When the images on the standard screen are displayed on a wide-screen television or monitor device which has a function for converting the aspect ratio in a lateral direction and a vertical direction of a sampling signal, the lateral direction is widened or the vertical direction is reduced. For this reason, the images are extended laterally or the images are reduced vertically, and thus distorted images are displayed. In such display devices having the function for switching between the standard images and the wide images, image data, which are reduced or enlarged by the opposite scaling to the scaling in the display devices, are created to be output to the display devices, so that the images can be displayed with the original ratio. When, however, such images are displayed on the display devices having a wide-size screen which does not have the switching function, a defect such as an image distorted to an opposite direction occurs.
The image processing devices which display the virtual objects such as game machines do not generally cope with various screen ratios, and even if they cope with the various ratios, defects occur in the display devices which do not have the function for switching between the wide-size screen and the standard screen in the image processing system which reduce or enlarge images with the scaling opposite to the scaling in the display devices. Particularly in the radar images where a predetermined area in the three-dimensional virtual space is expressed by reduced figure or the like, images in which the wide-screen display devices are taken into consideration are not processed, and even when the ratio of the image on the main screen is switched, the size of the visual field display of the radar portion is not changed. Further, in the form where the ratio is switched in the display device, a range which is actually in the visual field is different from the visual field display of the radar, a shape of the radar frame on the radar display portion is distorted, and the arrangement relationship of the object in the three-dimensional space to be displayed on the radar is not accurate. Conventionally, the radar image is displayed as a fan-shaped or inverted triangular plane representing the detection space, and display contents are fixed ones which are looked down vertically. A range which is actually in the visual field does not match with the visual field display of the radar, and the radar images which are obtained by capturing the visual field area in an arbitrary direction from the visual point position in the virtual three-dimensional space in conjunction with the game images cannot be displayed on the wide-size screen without trouble.
The present invention is devised from the viewpoint of the above situation, and its object is to provide a game image display control program which is capable of allowing a range which is actually in a visual field to match with a visual field display of a radar even when a radar image is displayed on a display device with varied screen ratio, a game machine, and a storage medium.